PROJECT SUMMARY/ABSTRACT About 25% of the U. S. population concurrently suffers from a mental illness, yet the majority do not receive treatment. Some people lack access to treatment because of structural barriers, e.g., cost, provider shortages, or transportation limitations. Others do not seek treatment because of attitudinal barriers, e.g., desire for self- reliance or fear of stigma. Novel options for prevention and treatment are needed to address these barriers. Accordingly, Objective 3 of the NIMH Strategic Plan is to Develop New and Better Interventions that Incorporate the Diverse Needs and Circumstances of People with Mental Illnesses. This application proposes to develop an intervention, Crowdsourcing Mental Health (CMH), that responds to this objective. CMH is designed to overcome several treatment barriers in order to (1) treat mild to moderate mental illness, (2) prevent onset and relapse, and (3) increase general psychological well-being. In CMH, peers suffering from mental illness (or those who wish to maintain mental health or increase well-being) will complete an online training in providing an empirically informed intervention. Subsequently, the two peers will deliver the intervention to each other. This technology-supported and peer-delivered approach eliminates barriers of cost, travel, and practitioner availability. CMH may also circumvent attitudinal barriers, allowing participants to feel self-reliant and avoid stigma. The proposed project has two aims: (1) prototype CMH's Web-based training, drawing on research on mental health-promoting processes, psychotherapy change mechanisms, and online education, and (2) test the training to determine its acceptability and efficacy in teaching the care provider role for the CMH program. (The present proposal does not test the full intervention, but instead aims to confirm whether online training can teach the identified caregiving skills. This step is needed prior to a full pilot trial because, if the training does not teach these skills, the intervention is unlikely to be effective. A pilot trial is planned after the conclusion of this award.) Aim 1 will apply the findings that mindfulness and social support are associated with mental health, perhaps through facilitating emotion regulation, which is disrupted in most mental illnesses. The training, then, will be designed to enhance skills of raising a partner's mindfulness and providing supportive statements and avoiding toxic ones. In Aim 2, adults with mild psychopathology will undergo the training. Before and after training, they will participate in mock CMH sessions with a researcher and their performance will be evaluated. They will also provide feedback on the training. This project lays the groundwork for testing the full CMH program's efficacy for various mental disorders and will train the applicant to become an independent scientist who investigates processes promoting mental health and translates findings into innovative treatments. CMH can have a positive impact by reducing the burden of mental illness, treating mild to moderate mental illness and preventing onset and relapse in people who are unable or unwilling to seek traditional treatment.